arm64: dts: mediatek: mt6795: Add CPUX system timer node

Add a node for mt6795-systimer: this is necessary to start the
System Timer(s) for all cores, finally making CNTVCT_EL0 usable.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220729093536.27623-1-angelogioacchino.delregno@collabora.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>